Total Synthesis of Eupomatilones 1, 2, and 5 by Enantioselective [2,3]-Wittig Rearrangement

In this study, the asymmetric total synthesis of eupomatilones 1, 2, and 5 has been accomplished. These compounds are lignan congeners containing a biaryl system bearing an α‐methylene γ‐lactone. They were isolated from the Australian shrub Eupomatia bennettii. Two chiral centers were constructed en...

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Bibliographic Details
Published in:European journal of organic chemistry 2013-02, Vol.2013 (4), p.721-727
Main Authors: Hirokawa, Yoshimi, Kitamura, Maria, Mizubayashi, Makoto, Nakatsuka, Rie, Kobori, Yuya, Kato, Chiharu, Kurata, Yuki, Maezaki, Naoyoshi
Format: Article
Language:English
Subjects:
Asymmetric synthesis
Enantioselectivity
Lignans
Natural products
Rearrangement
Total synthesis
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Summary:In this study, the asymmetric total synthesis of eupomatilones 1, 2, and 5 has been accomplished. These compounds are lignan congeners containing a biaryl system bearing an α‐methylene γ‐lactone. They were isolated from the Australian shrub Eupomatia bennettii. Two chiral centers were constructed enantioselectively by the asymmetric [2,3]‐Wittig rearrangement of highly oxygenated biaryl compounds, using a bis(oxazoline) chiral ligand. Optimization of the key reaction using nBuLi as the base and ether as the co‐solvent increased the enantioselectivity to 88–91 % ee. An asymmetric total synthesis of eupomatilones 1, 2, and 5 was carried out. The asymmetric [2,3]‐Wittig rearrangement of biarylmethyl ethers was used for the construction of the chiral centers, using a bis(oxazoline) chiral ligand. Optimization of the reaction conditions enabled the synthesis of eupomatilones 1, 2, and 5 with high enantioselectivities (88–91 % ee).
ISSN:1434-193X
1099-0690
DOI:10.1002/ejoc.201201247